Abstract: A planar power combiner/divider device comprises a metallic layer on an insulating substrate. The metallic layer is configured to have an output (input) neck portion (12) which extends into a purely tapered portion (16) which in turn splits into n tapering conductors (1 to 5), the terminal portions of which constitute input (output) ports. The overall length (L) of the metallic layer between a junction (14) of the neck and purely tapering portions to each input (output) port being substantially constant and equal to substantially half the wavelength of the lowest design frequency and the distance x from the junction (14) to the (first) split into tapering conductors is selected so as to avoid transverse resonance at the desired frequencies.

Abstract: A broadband balun, suitable for feeding a spiral antenna, has a balanced port (20) comprising two adjacent strip conductors (16,17; 36,37) which are coupled to the unbalanced port (6) by respective paths of the same effective electrical lengths. The paths comprise respective strip transmission lines (9,10) having a common ground conductor (3; 44) which terminates in a transition to the balanced line (19), and further comprise slot line means (11; 21) and strip transmission line-to-slot line coupling means (14,15) so arranged as in operation to provide in the two strip conductors (16,17; 36,37) from an RF signal at the unbalanced port (6) signals of mutually opposite phases with respect to the common ground conductor (3; 44).